South African Journal for Science and Technology ISSN: (Online) 2222-4173, (Print) 0254-3486 PagePage 1 of i of 17 ii OriginalInhoudsopgawe Research The anatomy and histochemistry of Grewia lasiocarpa E. Mey. ex Harv. (Malvaceae) Authors: Grewia lasiocarpa E. Mey. ex Harv is commonly known as the forest raisin(s) due to its edible Nneka A Akwu red-brown 4-lobed fruit(s), which turn black as they age. The genus is easily recognised by Yougasphree Naidoo Moganavelli Singh its distinctive morphology (edible fruits, crystals, trichomes) and abundant medicinal properties (antimicrobial, anti-infl ammatory, antioxidant). In order to distinguish this Affi lia ons: species from other Grewia species, this study aimed to describe the morphology, University of KwaZulu-Natal, Durban, South Africa ultrastructure of the leaves, stem bark and secretory structures of G. lasiocarpa using micro- scopic techniques and histochemical tests. he morphological and anatomical studies Corresponding author: revealed the presence of glandular trichomes. One type of peltate, three types of capitate Nneka A Akwu E-mail: [email protected] and non-glandular (simple, stellate, multangulate-stellate) trichomes were found on the leaves and stem bark of G. lasiocarpa. The histochemical investigation revealed that certain Dates: primary and secondary metabolites such as starch, protein, mucilage, lignin (polyphenols) Received: 13/05/20 Accepted: 16/09/20 and alkaloids are present in the leaves, stem bark and indumentum. This is the fi rst report on Published: 24/11/20 the morphological, ultrastructure and histochemical studies of leaves and stem bark of Grewia lasiocarpa. This structural characterisation of the leaves and stem bark would help to How to cite this ar cle: Akwu Nneka A, Naidoo distinguish this species from others in this genus, its ascertain authenticity, contribute to the Yougasphree, Singh pharmacognostic usage and general knowledge. Moganavelli, The anatomy and histochemistry Keywords: Grewia lasiocarpa; capitate trichome; peltate trichome; mucilaginous idioblasts; of Grewia lasiocarpa E. histochemistry Mey. ex Harv. (Malvaceae), Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 39(1) (2020). h ps://doi.org/10.36303/ Die anatomie en histochemie van Grewia lasiocarpa E. Mey. ex Harv. (Malvaceae): Grewia SATNT.2020.39.1.793 lasiocarpa E. Mey. ex Harv. staan in die algemeen bekend as bosrosyntjie vanweë sy eetbare, rooi-bruin, 4-lobbige vrugte, wat swart word soos hulle verouder. Die genus Grewia word ’n Afrikaanse vertaling van die manuskrip is aanlyn maklik herken aan hul uitsonderlike morfologie (eetbare vrugte, kristalle, trigome) en beskikbaar by h p://www. oorvloedige medisinale kenmerke (antimikrobies, anti-infl ammatories, anti-oksidant). Om satnt.ac.za/index.php/satnt/ hierdie spesie van die ander Grewia-spesies te onderskei, is met die studie beoog om die ar cle/view/793 morfologie, ultrastruktuur van die blare, stingelbas en sekresie-strukture van G. lasiocarpa te Copyright: beskryf aan die hand van mikroskopiese tegnieke en histo chemiese toetse. Die morfologiese © 2020. Authors. en anatomiese studies het die teenwoordigheid van klieragtige trigome getoon. Een tipe Licensee: Die Suid- Afrikaanse Akademie vir skildvormig, drie tipes knobbelvormig en nie-klieragtige (enkelvoudig, stervormig en Wetenskap en Kuns. This veelkantig-stervormig) trigome kom op die blare en stingelbas van G. lasiocarpa voor. Die work is licensed under histochemiese ondersoek het getoon sekere primêre en sekondêre metaboliete soos stysel, the Crea ve Commons A bu on License. proteïene, slym, lignien (polifenole) en alkaloïede kom in die blare, stingelbas en haarkleed voor. Hierdie is die eerste verslag oor die studie van die morfologie, ultrastruktuur en histochemie van die blare en stingelbas van Grewia lasiocarpa. Die kenmerke van die blare en stingelbas sal geskik wees om hierdie spesie van die ander in hierdie genus te onderskei, sy outentisiteit te bevestig en by te dra tot die farmakognosiese gebruike en algemene kennis. Sleutelwoorde: Grewia lasiocarpa; knobbelvormige trigome; skildvormige trigome; slymerige idioblaste; histochemie. h p://www.satnt.ac.za 91 Open Access Page 2 of 17 Original Research Introduc on The main aim and objective of this study is to investigate the morphology, ultrastructure and histochemistry of the The family Malvaceae, commonly known as mallow leaves and stem bark of G. lasiocarpa using conventional [formerly Sparrmanniaceae or Tiliaceae] (Johnson 1990; compound light, stereomicroscopy, fl uorescence and elec- Baser 1995; Ibrahim et al. 2018). They are found in tropical tron microscopy (Scanning electron microscopy [SEM] and and temperate regions and comprises of approximately transmission electron microscopy [TEM]) and comparing 3020 species in 192 genera with fourteen subtribes (Morton our results with other reported Grewia species. 1987; Nep et al. 2013). A previous taxonomic classifi cation scheme assigned Grewia as the only genus that produces Materials and methods edible fruits (Morton 1987), however there are several genera in the Malvaceae family that produce edible fruits Material used e.g. Abelmoschus, Azanza, Corchorus and Dombeya species. Healthy plant organs (leaves and stem bark) of Grewia lasiocarpa were harvested from the Umdoni Trust Park area, The genus Grewia, named after Nehemiah Grew (1641– southern KwaZulu-Natal, South Africa. The material was 1712), is predominant in South Africa, Arab, Madagascar, stored in air-tight bags on ice. The taxonomic identifi cation Himalayan regions, India, Pakistan, China, Myanmar, was done by Dr. Syd Ramdhani, curator of the School of Pacifi c islands (Tonga and Samoa), Malaysia, Thailand, Life Sciences, University of KwaZulu-Natal and voucher northern Australia and Bangladesh, with a total of 690 specimens were deposited at the Ward Herbarium, School published binomials (Bayer and Kubitzki 2003; Wahlert et of Life Sciences, Westville Campus with herbarium number al. 2015). In South Africa, there are 27 indigenous species Nneka 002. e.g. G. occidentalis, G. fl avescens and G. bicolor (Boon and Pooley 2010). Stereomicroscopy The morphology and density of the various trichomes Grewia lasiocarpa is usually found on rock outcrops, along present on the adaxial and abaxial surfaces of the randomly the coast to the mist-belt forest of Eastern Cape to KwaZulu- selected fresh whole leaves of emergent (< 1 cm), young Natal and also in tropical forests and margins (Boon and (1–5 cm) and mature leaves (5–10 cm) as well as randomly Pooley 2010). selected photosynthetic/green, herbaceous youngish stem The microscopic examination of the structural charac- pieces were examined. Images were captured with a Nikon terisation of plants during growth, development, genetic AZ100 stereomicroscope equipped with an AZ-LED ring, a manipulations and breeding is vital because the obser- Nikon Fibre illuminator and NIS-D Elements Software. vations derived from these examinations have been re- Sample prepara on: electron and light micro- markable (Payne 1978; Svoboda et al. 2000). Amongst the scopy important structural features are trichomes which could be glandular or non-glandular (Naidoo et al. 2011; Raghu et Scanning electron microscopy (SEM) al. 2019; Bantho et al. 2020). The importance of a compre- A scanning electron microscope was used to reveal the hensive morphological analysis of plants cannot be morphology and distribution of the trichomes present on overruled as this is useful in the verifi cation of authenticity, the leaf surfaces (adaxial and abaxial sides). The leaves ascertainment of the economic importance, determination were randomly selected with respect to their relative sizes of the best processing method and detection of foreign viz., of Grewia lasiocarpa. bodies (Svoboda et al. 2000; Ibrahim et al. 2018). Geogra- phical location infl uences the phytocompounds present in The fresh leaves from the three developmental stages of plants, because of abiotic factors such as varied climate, growth and stem bark portions were cut into small pieces temperature, rainfall, altitude, day length and UV-radia- approximately 2–3 x 4.0 mm2 and a similar technique of tion. These factors directly affect the biosynthesis of scanning electron microscopy (SEM) described by Naidoo secondary metabolites (Khalid et al. 2012). et al. (2013) was used with slight modifi cations in the use of 2.5% glutaraldehyde and 0.5% osmium tetroxide (OsO4) for In general, plants cannot survive without the primary primary and secondary fi xation respectively. metabolites but the absence of certain secondary meta- bolites will not result in instantaneous death but rather Freeze drying long-term damage to the physiological functions (Agostini Another set of fresh pieces from the three developmental et al. 2012). The presence of primary metabolites has been stages of G. lasiocarpa leaves and stem bark were placed in reported in the leaves and stem bark of G. lasiocarpa (Akwu liquid nitrogen (-196°C), after which the sections were et al. 2019; Akwu et al. 2019). There are few reports on the further frozen in an Edwards Modulyo freeze dryer morphology and ultrastructure of the leaves, fl owers and (Edwards High Vacuum International Ltd., UK), at -40 to stem bark of Grewia spp. e.g. G. laevigata Vahl (Sankhyan et -60°C in a vacuum of 10-1 Torr for 72 h. The samples were al. 2008), G. multifl ora, G. huluperakensis, G. polygama and G. stuck to brass stubs with carbon conductive tape, gold laevigata (Chung 2005). These species exhibit